It should be noted that the Ice and Hydro-Vipers are actually part of the Cobra Eels/Snow Serpents.[1][2]

Python Patrol

Python Patrol is a codename given to a subgroup of Vipers and other Cobra troops whose uniforms have undergone the "pythonization" process.[3] This renders their uniforms immune to radar and other forms of electronic detection. The unit has been led by both Copperhead and Major Bludd. In one instance, Zarana led a unit on an attack on G.I. Joe's headquarters, the Pit.

Vipers in Python Patrol:

Python H.E.A.T.-Viper

Python Laser-Viper

Python Rock-Viper

Python S.A.W.-Viper

Python Tele-Viper

Python Viper

Others

The following aren't Vipers per se, but also fill the role of "faceless Cobra troopers."